1. Field of the Invention
The present invention relates to a light-sensitive composition suitable for producing a presensitized plate for use in making lithographic printing plates (hereinafter referred to as "PS plate(s).revreaction.), IC circuits, photomasks or the like and more particularly it relates to a negative working light-sensitive composition comprising a photo-crosslinkable polymer compound, which exhibits excellent wear resistance when it is photo-hardened.
2. Prior Art
Photo-crosslinkable materials which crosslink through addition cyclization reaction are well known and widely used as a main component of a light-sensitive composition, which is used for, for example, the manufacture of PS plates. Useful examples of such kind of photo-crosslinkable compounds include polymer compounds having maleimido groups in their side chains and polymer compounds having photodimerizable unsaturated double bonds adjacent to aromatic rings such as those having cinnamyl groups, cinnamylidene groups, chalcone groups and the like.
Negative working PS plates using those photo-crosslinkable polymer compounds can be classified into two types, i.e., the alkali-developable type PS plates whose unexposed potions are removed (or developed) with an aqueous alkaline developer and the solvent-developable type PS plates whose unexposed portions are removed (or developed) with an organic solvent type developer, and to which type PS plates belong depends on the properties of the photo-crosslinkable polymer compounds used therein. Recently, the former type has become of major interest from the viewpoint of safety in operation and health of operators.
As the method for making the photo-crosslinkable polymer compounds alkali-soluble, there have been known a method where the polymer compounds are prepared by copolymerizing low-molecular-weight-compounds having photo-crosslinkable groups and polymerizable unsaturated bonds with methacrylic acid or acrylic acid such as disclosed in Japanese Patent Unexamined Publication (hereinafter referred to as "J.P. KOKAI") No. 52-988 (=U.S. Pat. No. 4,079,041) and Japanese Patent Publication for Opposition Purpose (hereinafter referred to as "J.P. KOKOKU") No. Sho 49-28122 (=U.S. Pat. No. 4,297,470), a method where the polymer compounds are prepared by copolymerizing low-molecular-weight-compounds having photo-crosslinkable groups and polymerizable unsaturated bonds with maleic anhydride and hydrolyzing the resulted compounds such as disclosed in J.P. KOKOKU No. Sho 57-56485, a method where polymeric carboxylic acids are prepared from polymer compounds containing carboxylic acid anhydride moieties while introducing photo-crosslinkable groups thereinto through polymer reaction such as disclosed in J.P. KOKAI No. Sho 59-218440, a method where photo-crosslinkable groups are introduced into polyacrylic acids through polymer reaction such as disclosed in J.P. KOKAI No. Sho 48-74594 and the like.
However, light-sensitive compositions comprising photo-crosslinkable polymer compounds described above have a drawback that they have poor wear resistance when they are photo-hardened and hence they cannot exhibit sufficient printing durability when they are used in lithographic printing plates.